PROJECT SUMMARY/ABSTRACT This proposal outlines a 5-year translational research project to explore the mechanisms underlying the HIV risk associated with pharmacologic doses of exogenous sex hormones (via hormonal contraceptives). Emerging data suggests that certain hormonal contraceptives may induce mucosal and systemic immune changes that could increase the risk of infection with HIV. While several studies have aimed to characterize immunologic changes in women using hormonal contraceptives, the nature and the magnitude of these immune changes have not been adequately defined due to limitations in study design rigor, and small and statistically underpowered sample sizes. There is limited comprehensive data or comparative data on the effect of different types of contraceptives on innate and adaptive immunologic markers of HIV susceptibility. Without this research, we cannot effectively counsel our patients on contraceptive selection. Characterization of potential individual-level factors, such as the presence of bacterial vaginosis (BV), that may alter a woman's risk profile with contraceptive use, could lead to individualized decision-making about contraceptive choice and would have profound implications for global health especially in HIV-endemic areas. We propose to prospectively recruit cohorts of HIV-uninfected women initiating hormonal contraception to characterize systemic and lower genital track innate and adaptive immunologic changes that occur over the course of 1 year. This study will test the overarching hypothesis that hormonal contraceptives induce systemic and mucosal immune changes capable of altering susceptibilities and/or responses to diseases including HIV infection, and that these effects vary markedly in nature and magnitude by contraceptive type and will be modified by the vaginal microenvironment. The aims are: 1) To determine the immunologic alterations in female genital and systemic immune profile associated with depot medroxyprogesterone acetate (DMPA), Etonogestrel impant (Eng-Implant) and Levonorgestrel IUD (Lng-IUD). We hypothesize that HIV target immune cells within the female genital tract of HIV-uninfected at-risk women will increase following contraceptive initiation. Further, because the anticipated mucosal immune changes with progestin-only contraceptives are, to a large extent, mediated via estrogen suppression, we hypothesize the impact of the Lng-IUD (with minimal to no anti-estrogen effect) and Eng-Implant (with milder anti-estrogen effect) will be significantly less pronounced compared with that of DMPA. 2) To evaluate the vaginal microenvironment as a moderator of genital and systemic immune profile changes and changes in tissue infectivity following exposure to these three commonly used hormonal contraceptives. Based on our earlier findings, we hypothesize that immunologic changes induced with hormonal contraception will be more pronounced in the setting of BV. The outcomes of the proposed study could have significant global clinical implications for safe individualized contraceptive counseling and decision-making for women at risk for HIV/AIDS.